# Access control overview

Access Control in AgentLink determines **which tools a user or tenant can see and execute** through your MCP server.
Rules can be mapped to **roles** or **permissions** and enforced dynamically from JWT claims.

> Discovery is enforced: tools that are not allowed by your rules are **not returned** by the MCP `listTool` function, so AI agents cannot see or call them.


## Page layout

The **Access Control** page shows a searchable table of rules and an action to create new ones.

**Table columns**

- **Mapping name** — Friendly name of the rule (e.g., “Only admin can delete”).
- **Mapping type** — “Role based” or “Permission based”.
- **Tools** — One or more tools the rule controls.
- **Assignments** — Number of roles or permissions assigned.
- **Last updated** — When the rule was last modified.
- **Actions** — Edit or delete.


Use the **Add rule** button (top-right) to create a new rule.

![access-control-page](/assets/access-control.b0e08a84975b8aa4bc708bd08f50428786f8f8ed10975ff86116072eb8ebf6ee.b925d42d.png)

## Creating a rule

Click **Add rule** to open the rule dialog.

**Fields in the dialog**

- **Mapping name** — A concise label for the rule.
- **Description** — Optional context for admins (what/why).
- **Tools** — Select one or more tools this rule governs.
- **Mapping type** *(immutable after creation)*
  - **Map to roles** — Control access based on user roles.
  - **Map to permission** — Control access based on specific permissions/entitlements.
- **Assign roles / Assign permissions** — Choose the roles or permissions that grant access.


Click **Save** to create the rule. It takes effect immediately for discovery and execution.

## Editing or deleting a rule

- **Edit:** Click the three-dot menu on a row and choose **Edit**. Update description, assignments, or tools (mapping type cannot change). Save to apply.
- **Delete:** Use the three-dot menu → **Delete**. Removing the rule immediately revokes discovery and access for the affected tools unless covered by another rule.


## How enforcement works

1. **Discovery filter**
When an AI agent calls MCP `listTool`, AgentLink evaluates the caller’s JWT claims.
Tools not allowed by any matching rule are **omitted** from the response.
2. **Execution gate**
When a tool is invoked, the same rule set is evaluated again. If no rule grants access, the call is blocked and logged.
3. **RBAC and PBAC**
  - **Role-based (RBAC):** Access is granted if the user has one of the assigned roles.
  - **Permission-based:** Access is granted if the user has one of the assigned permissions/entitlements.


Rules can target individual tools or sets of tools and are evaluated per request using the caller’s JWT claims.

## Examples

### Example 1 — Role-based access

Allow only admins to call `Delete_expense`.

- **Mapping name:** Only admin can delete
- **Tools:** `Delete_expense`
- **Mapping type:** Map to roles
- **Assign roles:** `admin`


Result: Only users with the `admin` role will see `Delete_expense` in `listTool` and can execute it.

### Example 2 — Permission-based access

Grant `read_customer` permission holders access to `get_customer_profile`.

- **Mapping name:** Customer profile read
- **Tools:** `get_customer_profile`
- **Mapping type:** Map to permission
- **Assign permissions:** `read_customer`


Result: Users without `read_customer` will not see or use this tool.

## Testing access

Use the Access Control page to:

- Search for a tool and verify which rules apply.
- Inspect **Assignments** to confirm the intended roles/permissions.
- After changes, validate as the target user (or via your app) that `listTool` returns only the allowed tools.


For deeper visibility, check **Monitoring → Logs** to see discovery and execution outcomes.

## Best practices

- Prefer **least privilege**: limit high-impact tools to specific roles or permissions.
- Use clear mapping names and descriptions so admins understand intent.
- Keep mapping type stable: choose “roles” or “permissions” based on your identity model before creating the rule.
- Periodically review unassigned or stale rules and clean them up.
- Combine Access Control with **Policies** for conditional enforcement (amount thresholds, approvals, etc.).


## Related topics

- [Managing Tools](/agent-link/tools/managing-tools)
- [Policies & Guardrails](/agent-link/policies/overview)
- [Monitoring & Logs](/agent-link/monitoring/overview)